Hi!
TArray<UZ_TXDATA*> MyCommandArray; is an array of pointers to objects of type UZ_TXDATA.
Objects are instantiations of a class/blueprint but they are not the class itself and pointers to these objects aren’t either so you cannot drag a blueprint into an array of pointers. You can instantiate objects of type UZ_TXDATA (e.g. using the Construct ... blueprint node) at runtime and then add the reference to the array or set it at a specific index.